1. Field of the Invention
The present invention relates to a transfusion filtering device for preventing infection caused by bacteria in blood transfusion and for preventing foreign materials from entering a human body.
2. Description of the Prior Art
A large amount of a transfusing liquid is injected into a patient in many medical treatments. It is necessary to use a transfusion filtering device in order to prevent infection caused by bacteria and to prevent foreign materials from entering the human body in injecting a transfusing liquid into a patient. The conventional transfusion filtering portion is defective in that, if an air stays in the filtering portion, the area of the filtering section capable of performing the filtering function is diminished, leading to a low filtering capability. For overcoming the difficulty, a transfusion filtering device provided with an air-releasing port is proposed in, for example, Japanese Published Examined Patent Application No. 1-17383.
The transfusion filtering device provided with an air-releasing port is constructed such that an air stays within the filter under a predetermined posture of the filter. The air-releasing port is formed in the air-staying portion of the filter. It follows that the transfusion filtering device noted above is defective in that a sufficient air-releasing effect cannot be obtained if the filter is used in another optional posture.
It should also be noted that the filtering section is planar in the conventional transfusion filtering device, making the filter bulky. In other words, it is difficult to miniaturize the transfusion filtering device while maintaining a high filtering capacity.
What should also be noted is that, in actually using a transfusion filtering device, it is necessary to fill the transfusion filtering device with a transfusing liquid and, at the same time, to perform a priming operation (air releasing operation) in order to remove bubbles remaining within the filter. To be more specific, it is necessary to release the remaining bubbles by, for example, turning the transfusion filtering device filled with a transfusing liquid upside down or by striking with fingers the filter filled with the transfusing liquid.